1. Field of the Invention
The present invention relates generally to flexible magnetic storage media, and more particularly to flexible disk storage media formatted to contain programming operable on more than one computer.
2. Description of the Prior Art
In recent years, there has been a surge in the popularity of the personal or microcomputer. Such computers are currently being utilized in a variety of applications in the home, business, scientific and educational environments. Uses for these personal computers range from entertainment such as games to sophisticated data processing applications. The current demand for personal computers has spurred development of various different types, each with its own software requirements.
Application programs and external data storage are generally encoded onto flexible disk storage media. These disk storage media typically comprise a thin base film substrate of a flexible material such as polyethylene teraphthalate overlayed by a layer of magnetic recording material such as ferric oxide. The disk portion which is recorded upon typically constitutes an area extending from the outer perimeter to approximately two-thirds of the distance to the disk axis and includes a series concentrically arranged data tracks. These tracks are arbitrary concentric portions which the computer is adapted to recognize and read.
The magnetic recording layer itself comprises a plurality of magnetic particles whose orientation is random within a binder. These particles comprising the magnetic layer possess magnetic domains, which are randomly oriented in the absence of a magnetic field. When a field is applied by a read/write head, the magnetic domains become oriented parallel to the lines of force of the applied field. A change in the field creates a magnetic flux reversal, which is the means by which data is stored. Correspondingly, data is read from the disk by inducing a current in the read/write head by passing the head over such a flux reversal. A series of flux reversals results in a binary sequence, which may then be interpreted by the computer according to a set of instructions given it.
A five and one-quarter inch diameter flexible disk contains approximately forty data tracks and may be divided, for indexing purposes, into various angular sectors. Each sector must contain an appropriate computer language code series to signify its existence to the computer. This code series is known as a header, and the process by which the disk is divided into individually identified sectors is known as formatting. Formatting the disk simplifies storing and accessing physically or logically related or unrelated sets of information or data. For example, a popular video game program may occupy only a fraction of the available storage space. By formatting the disk, several games may be stored on a single disk, and each can be individually accessed. The personal computers currently commerically available each contain their own hardware/software operating systems which may interpret a binary sequence differently. As a result data written on a disk through one computer cannot be read from the disk by another and each disk must be formatted to contain programming compatible with the appropriate target computer. None of the prior art addresses the problem of formatting a single flexible disk for use with multiple computer systems of different compatibilities.
U.S. Pat. No 4,377,825 issued to Kasubichi, et al., discloses an apparatus for interfacing with an ordinary pocket calculator to give it external information storage capabilities. U.S. Pat. No. 4,366,511 issued to Ranalli describes a method and apparatus for formatting a memory disk. The method of Ranalli is directed to formatting multiple headers on a single disk, and is not a multiple system formatting method. U.S. Pat. No. 4,298,897 issued to Arter, et al., discloses a means for increasing track density of a magnetic recording medium by recording narrower tracks. U.S. Pat. No. 3,226,700 issued to Miller describes a method for referencing and accessing serially recorded data.
In view of the prior art, there remains a need for a disk storage medium a method for recording information on the disk storage medium which may be read by more than one computer system.